The present disclosure relates generally to medical devices. More particularly, it relates to iliac branch devices for excluding abdominal aortic aneurysms to maintain perfusion of internal iliac arteries.
The functional vessels of human and animal bodies, such as blood vessels and ducts, occasionally weaken or even rupture. For example, the aortic wall can weaken, resulting in an aneurysm. Upon further exposure to hemodynamic forces, such an aneurysm can rupture. One study found that in Western European and Australian men who are between 60 and 75 years of age, aortic aneurysms greater than 29 mm in diameter are found in 6.9% of the population, and those greater than 40 mm are present in 1.8% of the population.
One surgical intervention for weakened, aneurysmal, or ruptured vessels involves the use of an endoluminal prosthesis such as a stent graft. Such a prosthesis may provide some or all of the functionality of the original, healthy vessel and/or preserve any remaining vascular integrity by replacing a length of the existing vessel wall that spans the site of vessel failure. It is preferable for the prosthesis to seal off the failed portion of the vessel. For weakened or aneurysmal vessels, even a small leak in the prosthesis may lead to the pressurization of or flow in the treated vessel which may aggravate the condition that the prosthesis was intended to treat. A prosthesis of this type can treat, for example, aneurysms of the abdominal aortic, iliac, or renal arteries. For instance, a prosthesis may be used to span an aneurysm which has occurred in or associated with an iliac artery.
In many cases, such a damaged or defective portion of the vasculature may include a branch vessel. For example, the celiac, superior mesenteric, left common carotid, and renal arteries are branch vessels of the aorta, and the internal iliac artery is a branch vessel of the common iliac artery. If the branch vessel is blocked by the prosthesis, the original blood circulation is impeded, and the patient can suffer. If, for example, the celiac artery is blocked by the prosthesis, the patient can experience abdominal pain, weight loss, nausea, bloating, and loose stools associated with mesenteric ischemia. The blockage of any branch vessel is usually associated with unpleasant or even life-threatening symptoms. Hence, it has been proposed to provide a prosthesis having a side branch which, when deployed, is positioned over the opening to a branch vessel. For example, the iliac branch of a bifurcated aortic prosthesis can be designed to extend into and/or provide flow to the corresponding internal iliac artery. Such a prosthesis is commonly referred to as an iliac branch device (IBD).
Furthermore, an aneurysm may extend into the branch vessel. For example, the aneurysm can progress distally from the aorta through the iliac bifurcation and into the common iliac arteries. The aneurysm may progress a sufficient distance to include one or both internal iliac arteries. An aneurysm including one internal iliac artery is known as a unilateral iliac aneurysm, and an aneurysm including both internal iliac arteries is known as a bilateral iliac aneurysm. Deploying a prosthesis into the branch vessel may help to prevent expansion and/or rupture of such an aneurysm. Another prosthesis such as, for example, a stent graft also can be deployed through the side branch and into the branch vessel to treat the aneurysm extending into the branch vessel and/or provide a blood flow path to the branch vessel.
To accommodate the anatomy of a patient and/or the preference of a physician, the side branch of such a prosthesis typically is biased either to the left or the right side of the body of the prosthesis. For example, an IBD designed to be positioned within one common iliac artery may have a side branch biased to the left and another IBD designed to be positioned in the other common iliac artery may have a side branch biased to the right. Because such IBDs may be mirror images of one another, the two IBDs may not be interchangeable with one another. In other words, each IBD may be suitable for placement only in the common iliac artery for which it was designed, and not in the other common iliac artery.